/*
 * Copyright (c) 1982, 1986, 1988, 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)tcp_subr.c	8.1 (Berkeley) 6/10/93
 * tcp_subr.c,v 1.5 1994/10/08 22:39:58 phk Exp
 */

/*
 * Changes and additions relating to SLiRP
 * Copyright (c) 1995 Danny Gasparovski.
 *
 * Please read the file COPYRIGHT for the
 * terms and conditions of the copyright.
 */

#define WANT_SYS_IOCTL_H
#include <stdlib.h>
#include "slirp/slirp.h"

/* patchable/settable parameters for tcp */
int tcp_mssdflt = TCP_MSS;
int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ;
int tcp_do_rfc1323 = 0; /* Don't do rfc1323 performance enhancements */
int tcp_rcvspace;       /* You may want to change this */
int tcp_sndspace;       /* Keep small if you have an error prone link */

/*
 * Tcp initialization
 */
void tcp_init() {
        tcp_iss = 1; /* wrong */
        tcb.so_next = tcb.so_prev = &tcb;

        /* tcp_rcvspace = our Window we advertise to the remote */
        tcp_rcvspace = TCP_RCVSPACE;
        tcp_sndspace = TCP_SNDSPACE;

        /* Make sure tcp_sndspace is at least 2*MSS */
        if (tcp_sndspace < 2 * (min(if_mtu, if_mru) - sizeof(struct tcpiphdr)))
                tcp_sndspace = 2 * (min(if_mtu, if_mru) - sizeof(struct tcpiphdr));
}

/*
 * Create template to be used to send tcp packets on a connection.
 * Call after host entry created, fills
 * in a skeletal tcp/ip header, minimizing the amount of work
 * necessary when the connection is used.
 */
/* struct tcpiphdr * */
void tcp_template(tp) struct tcpcb *tp;
{
        struct SLIRPsocket *so = tp->t_socket;
        struct tcpiphdr *n = &tp->t_template;

        n->ti_mbuf = NULL;
        n->ti_x1 = 0;
        n->ti_pr = IPPROTO_TCP;
        n->ti_len = htons(sizeof(struct tcpiphdr) - sizeof(struct ip));
        n->ti_src = so->so_faddr;
        n->ti_dst = so->so_laddr;
        n->ti_sport = so->so_fport;
        n->ti_dport = so->so_lport;

        n->ti_seq = 0;
        n->ti_ack = 0;
        n->ti_x2 = 0;
        n->ti_off = 5;
        n->ti_flags = 0;
        n->ti_win = 0;
        n->ti_sum = 0;
        n->ti_urp = 0;
}

/*
 * Send a single message to the TCP at address specified by
 * the given TCP/IP header.  If m == 0, then we make a copy
 * of the tcpiphdr at ti and send directly to the addressed host.
 * This is used to force keep alive messages out using the TCP
 * template for a connection tp->t_template.  If flags are given
 * then we send a message back to the TCP which originated the
 * segment ti, and discard the SLIRPmbuf containing it and any other
 * attached SLIRPmbufs.
 *
 * In any case the ack and sequence number of the transmitted
 * segment are as specified by the parameters.
 */
void tcp_respond(tp, ti, m, ack, seq, flags) struct tcpcb *tp;
struct tcpiphdr *ti;
struct SLIRPmbuf *m;
tcp_seq ack, seq;
int flags;
{
        register int tlen;
        int win = 0;

        DEBUG_CALL("tcp_respond");
        DEBUG_ARG("tp = %lx", (long)tp);
        DEBUG_ARG("ti = %lx", (long)ti);
        DEBUG_ARG("m = %lx", (long)m);
        DEBUG_ARG("ack = %u", ack);
        DEBUG_ARG("seq = %u", seq);
        DEBUG_ARG("flags = %x", flags);

        if (tp)
                win = sbspace(&tp->t_socket->so_rcv);
        if (m == 0) {
                if ((m = m_get()) == NULL)
                        return;
#ifdef TCP_COMPAT_42
                tlen = 1;
#else
                tlen = 0;
#endif
                m->m_data += if_maxlinkhdr;
                *mtod(m, struct tcpiphdr *) = *ti;
                ti = mtod(m, struct tcpiphdr *);
                flags = TH_ACK;
        } else {
                /*
                 * ti points into m so the next line is just making
                 * the SLIRPmbuf point to ti
                 */
                m->m_data = (SLIRPcaddr_t)ti;

                m->m_len = sizeof(struct tcpiphdr);
                tlen = 0;
#define xchg(a, b, type)                                                                                                         \
        {                                                                                                                        \
                type t;                                                                                                          \
                t = a;                                                                                                           \
                a = b;                                                                                                           \
                b = t;                                                                                                           \
        }
                xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_int32_t);
                xchg(ti->ti_dport, ti->ti_sport, u_int16_t);
#undef xchg
        }
        ti->ti_len = htons((u_short)(sizeof(struct tcphdr) + tlen));
        tlen += sizeof(struct tcpiphdr);
        m->m_len = tlen;

        ti->ti_mbuf = 0;
        ti->ti_x1 = 0;
        ti->ti_seq = htonl(seq);
        ti->ti_ack = htonl(ack);
        ti->ti_x2 = 0;
        ti->ti_off = sizeof(struct tcphdr) >> 2;
        ti->ti_flags = flags;
        if (tp)
                ti->ti_win = htons((u_int16_t)(win >> tp->rcv_scale));
        else
                ti->ti_win = htons((u_int16_t)win);
        ti->ti_urp = 0;
        ti->ti_sum = 0;
        ti->ti_sum = cksum(m, tlen);
        ((struct ip *)ti)->ip_len = tlen;

        if (flags & TH_RST)
                ((struct ip *)ti)->ip_ttl = MAXTTL;
        else
                ((struct ip *)ti)->ip_ttl = ip_defttl;

        (void)ip_output((struct SLIRPsocket *)0, m);
}

/*
 * Create a new TCP control block, making an
 * empty reassembly queue and hooking it to the argument
 * protocol control block.
 */
struct tcpcb *tcp_newtcpcb(so) struct SLIRPsocket *so;
{
        struct tcpcb *tp;

        tp = (struct tcpcb *)malloc(sizeof(*tp));
        if (tp == NULL)
                return ((struct tcpcb *)0);

        memset((char *)tp, 0, sizeof(struct tcpcb));
        tp->seg_next = tp->seg_prev = (struct tcpiphdr *)tp;
        tp->t_maxseg = tcp_mssdflt;

        tp->t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE | TF_REQ_TSTMP) : 0;
        tp->t_socket = so;

        /*
         * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no
         * rtt estimate.  Set rttvar so that srtt + 2 * rttvar gives
         * reasonable initial retransmit time.
         */
        tp->t_srtt = TCPTV_SRTTBASE;
        tp->t_rttvar = tcp_rttdflt * PR_SLOWHZ << 2;
        tp->t_rttmin = TCPTV_MIN;

        TCPT_RANGESET(tp->t_rxtcur, ((TCPTV_SRTTBASE >> 2) + (TCPTV_SRTTDFLT << 2)) >> 1, TCPTV_MIN, TCPTV_REXMTMAX);

        tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;
        tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
        tp->t_state = TCPS_CLOSED;

        so->so_tcpcb = tp;

        return (tp);
}

/*
 * Drop a TCP connection, reporting
 * the specified error.  If connection is synchronized,
 * then send a RST to peer.
 */
struct tcpcb *tcp_drop(struct tcpcb *tp, int err) {
        /* tcp_drop(tp, errno)
                struct tcpcb *tp;
                int errno;
        {
        */

        DEBUG_CALL("tcp_drop");
        DEBUG_ARG("tp = %lx", (long)tp);
        DEBUG_ARG("errno = %d", errno);

        if (TCPS_HAVERCVDSYN(tp->t_state)) {
                tp->t_state = TCPS_CLOSED;
                (void)tcp_output(tp);
                tcpstat.tcps_drops++;
        } else
                tcpstat.tcps_conndrops++;
        /*	if (errno == ETIMEDOUT && tp->t_softerror)
         *		errno = tp->t_softerror;
         */
        /*	so->so_error = errno; */
        return (tcp_close(tp));
}

/*
 * Close a TCP control block:
 *	discard all space held by the tcp
 *	discard internet protocol block
 *	wake up any sleepers
 */
struct tcpcb *tcp_close(tp) struct tcpcb *tp;
{
        struct tcpiphdr *t;
        struct SLIRPsocket *so = tp->t_socket;
        struct SLIRPmbuf *m;

        DEBUG_CALL("tcp_close");
        DEBUG_ARG("tp = %lx", (long)tp);

        /* free the reassembly queue, if any */
        t = tcpfrag_list_first(tp);
        while (!tcpfrag_list_end(t, tp)) {
                t = tcpiphdr_next(t);
                m = (struct SLIRPmbuf *)tcpiphdr_prev(t)->ti_mbuf;
                remque(tcpiphdr2qlink(tcpiphdr_prev(t)));
                m_freem(m);
        }
        /* It's static */
        /*	if (tp->t_template)
         *		(void) m_free(dtom(tp->t_template));
         */
        /*	free(tp, M_PCB);  */
        free(tp);
        so->so_tcpcb = 0;
        soisfdisconnected(so);
        /* clobber input socket cache if we're closing the cached connection */
        if (so == tcp_last_so)
                tcp_last_so = &tcb;
        closesocket(so->s);
        sbfree(&so->so_rcv);
        sbfree(&so->so_snd);
        sofree(so);
        tcpstat.tcps_closed++;
        return ((struct tcpcb *)0);
}

void tcp_drain() { /* XXX */ }

/*
 * When a source quench is received, close congestion window
 * to one segment.  We will gradually open it again as we proceed.
 */

#ifdef notdef

void tcp_quench(i, errno)

        int errno;
{
        struct tcpcb *tp = intotcpcb(inp);

        if (tp)
                tp->snd_cwnd = tp->t_maxseg;
}

#endif /* notdef */

/*
 * TCP protocol interface to socket abstraction.
 */

/*
 * User issued close, and wish to trail through shutdown states:
 * if never received SYN, just forget it.  If got a SYN from peer,
 * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN.
 * If already got a FIN from peer, then almost done; go to LAST_ACK
 * state.  In all other cases, have already sent FIN to peer (e.g.
 * after PRU_SHUTDOWN), and just have to play tedious game waiting
 * for peer to send FIN or not respond to keep-alives, etc.
 * We can let the user exit from the close as soon as the FIN is acked.
 */
void tcp_sockclosed(tp) struct tcpcb *tp;
{

        DEBUG_CALL("tcp_sockclosed");
        DEBUG_ARG("tp = %lx", (long)tp);

        switch (tp->t_state) {

        case TCPS_CLOSED:
        case TCPS_LISTEN:
        case TCPS_SYN_SENT:
                tp->t_state = TCPS_CLOSED;
                tp = tcp_close(tp);
                break;

        case TCPS_SYN_RECEIVED:
        case TCPS_ESTABLISHED:
                tp->t_state = TCPS_FIN_WAIT_1;
                break;

        case TCPS_CLOSE_WAIT:
                tp->t_state = TCPS_LAST_ACK;
                break;
        }
        /*	soisfdisconnecting(tp->t_socket); */
        if (tp && tp->t_state >= TCPS_FIN_WAIT_2)
                soisfdisconnected(tp->t_socket);
        if (tp)
                tcp_output(tp);
}

/*
 * Connect to a host on the Internet
 * Called by tcp_input
 * Only do a connect, the tcp fields will be set in tcp_input
 * return 0 if there's a result of the connect,
 * else return -1 means we're still connecting
 * The return value is almost always -1 since the socket is
 * nonblocking.  Connect returns after the SYN is sent, and does
 * not wait for ACK+SYN.
 */
int tcp_fconnect(so) struct SLIRPsocket *so;
{
        int ret = 0;

        DEBUG_CALL("tcp_fconnect");
        DEBUG_ARG("so = %lx", (long)so);

        if ((ret = so->s = socket(AF_INET, SOCK_STREAM, 0)) >= 0) {
                int opt, s = so->s;
                struct sockaddr_in addr;
                memset(&addr, 0, sizeof(struct sockaddr_in));

                fd_nonblock(s);
                opt = 1;
                setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *)&opt, sizeof(opt));
                opt = 1;
                setsockopt(s, SOL_SOCKET, SO_OOBINLINE, (char *)&opt, sizeof(opt));

                addr.sin_family = AF_INET;
                if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
                        /* It's an alias */
                        switch (ntohl(so->so_faddr.s_addr) & 0xff) {
                        case CTL_DNS:
                                addr.sin_addr = dns_addr;
                                break;
                        case CTL_ALIAS:
                        default:
                                addr.sin_addr = loopback_addr;
                                break;
                        }
                } else
                        addr.sin_addr = so->so_faddr;
                addr.sin_port = so->so_fport;

                DEBUG_MISC((dfd,
                            " connect()ing, addr.sin_port=%d, "
                            "addr.sin_addr.s_addr=%.16s\n",
                            ntohs(addr.sin_port), inet_ntoa(addr.sin_addr)));
                /* We don't care what port we get */
                ret = connect(s, (struct sockaddr *)&addr, sizeof(addr));

                /*
                 * If it's not in progress, it failed, so we just return 0,
                 * without clearing SS_NOFDREF
                 */
                soisfconnecting(so);
        }

        return (ret);
}

/*
 * Accept the socket and connect to the local-host
 *
 * We have a problem. The correct thing to do would be
 * to first connect to the local-host, and only if the
 * connection is accepted, then do an accept() here.
 * But, a) we need to know who's trying to connect
 * to the socket to be able to SYN the local-host, and
 * b) we are already connected to the foreign host by
 * the time it gets to accept(), so... We simply accept
 * here and SYN the local-host.
 */
void tcp_connect(inso) struct SLIRPsocket *inso;
{
        struct SLIRPsocket *so;
        struct sockaddr_in addr;
        socklen_t addrlen = sizeof(struct sockaddr_in);
        struct tcpcb *tp;
        int s, opt;

        DEBUG_CALL("tcp_connect");
        DEBUG_ARG("inso = %lx", (long)inso);

        /*
         * If it's an SS_ACCEPTONCE socket, no need to socreate()
         * another socket, just use the accept() socket.
         */
        if (inso->so_state & SS_FACCEPTONCE) {
                /* FACCEPTONCE already have a tcpcb */
                so = inso;
        } else {
                if ((so = socreate()) == NULL) {
                        /* If it failed, get rid of the pending connection */
                        closesocket(accept(inso->s, (struct sockaddr *)&addr, &addrlen));
                        return;
                }
                if (tcp_attach(so) < 0) {
                        free(so); /* NOT sofree */
                        return;
                }
                so->so_laddr = inso->so_laddr;
                so->so_lport = inso->so_lport;
        }

        (void)tcp_mss(sototcpcb(so), 0);

        if ((s = accept(inso->s, (struct sockaddr *)&addr, &addrlen)) < 0) {
                tcp_close(sototcpcb(so)); /* This will sofree() as well */
                return;
        }
        fd_nonblock(s);
        opt = 1;
        setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *)&opt, sizeof(int));
        opt = 1;
        setsockopt(s, SOL_SOCKET, SO_OOBINLINE, (char *)&opt, sizeof(int));
        opt = 1;
        setsockopt(s, IPPROTO_TCP, TCP_NODELAY, (char *)&opt, sizeof(int));

        so->so_fport = addr.sin_port;
        so->so_faddr = addr.sin_addr;
        /* Translate connections from localhost to the real hostname */
        if (so->so_faddr.s_addr == 0 || so->so_faddr.s_addr == loopback_addr.s_addr)
                so->so_faddr = alias_addr;

        /* Close the accept() socket, set right state */
        if (inso->so_state & SS_FACCEPTONCE) {
                closesocket(so->s);        /* If we only accept once, close the accept() socket */
                so->so_state = SS_NOFDREF; /* Don't select it yet, even though we have an FD */
                                           /* if it's not FACCEPTONCE, it's already NOFDREF */
        }
        so->s = s;

        so->so_iptos = tcp_tos(so);
        tp = sototcpcb(so);

        tcp_template(tp);

        /* Compute window scaling to request.  */
        /*	while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
         *		(TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat)
         *		tp->request_r_scale++;
         */

        /*	soisconnecting(so); */ /* NOFDREF used instead */
        tcpstat.tcps_connattempt++;

        tp->t_state = TCPS_SYN_SENT;
        tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
        tp->iss = tcp_iss;
        tcp_iss += TCP_ISSINCR / 2;
        tcp_sendseqinit(tp);
        tcp_output(tp);
}

/*
 * Attach a TCPCB to a socket.
 */
int tcp_attach(so) struct SLIRPsocket *so;
{
        if ((so->so_tcpcb = tcp_newtcpcb(so)) == NULL)
                return -1;

        insque(so, &tcb);

        return 0;
}

/*
 * Set the socket's type of service field
 */
struct tos_t tcptos[] = {{0, 20, IPTOS_THROUGHPUT, 0},                         /* ftp data */
                         {21, 21, IPTOS_LOWDELAY, EMU_FTP},                    /* ftp control */
                         {0, 23, IPTOS_LOWDELAY, 0},                           /* telnet */
                         {0, 80, IPTOS_THROUGHPUT, 0},                         /* WWW */
                         {0, 513, IPTOS_LOWDELAY, EMU_RLOGIN | EMU_NOCONNECT}, /* rlogin */
                         {0, 514, IPTOS_LOWDELAY, EMU_RSH | EMU_NOCONNECT},    /* shell */
                         {0, 544, IPTOS_LOWDELAY, EMU_KSH},                    /* kshell */
                         {0, 543, IPTOS_LOWDELAY, 0},                          /* klogin */
                         {0, 6667, IPTOS_THROUGHPUT, EMU_IRC},                 /* IRC */
                         {0, 6668, IPTOS_THROUGHPUT, EMU_IRC},                 /* IRC undernet */
                         {0, 7070, IPTOS_LOWDELAY, EMU_REALAUDIO},             /* RealAudio control */
                         {0, 113, IPTOS_LOWDELAY, EMU_IDENT},                  /* identd protocol */
                         {0, 0, 0, 0}};

struct emu_t *tcpemu = 0;

/*
 * Return TOS according to the above table
 */
u_int8_t tcp_tos(so) struct SLIRPsocket *so;
{
        int i = 0;
        struct emu_t *emup;

        while (tcptos[i].tos) {
                if ((tcptos[i].fport && (ntohs(so->so_fport) == tcptos[i].fport)) ||
                    (tcptos[i].lport && (ntohs(so->so_lport) == tcptos[i].lport))) {
                        so->so_emu = tcptos[i].emu;
                        return tcptos[i].tos;
                }
                i++;
        }

        /* Nope, lets see if there's a user-added one */
        for (emup = tcpemu; emup; emup = emup->next) {
                if ((emup->fport && (ntohs(so->so_fport) == emup->fport)) ||
                    (emup->lport && (ntohs(so->so_lport) == emup->lport))) {
                        so->so_emu = emup->emu;
                        return emup->tos;
                }
        }

        return 0;
}

int do_echo = -1;

/*
 * Emulate programs that try and connect to us
 * This includes ftp (the data connection is
 * initiated by the server) and IRC (DCC CHAT and
 * DCC SEND) for now
 *
 * NOTE: It's possible to crash SLiRP by sending it
 * unstandard strings to emulate... if this is a problem,
 * more checks are needed here
 *
 * XXX Assumes the whole command came in one packet
 *
 * XXX Some ftp clients will have their TOS set to
 * LOWDELAY and so Nagel will kick in.  Because of this,
 * we'll get the first letter, followed by the rest, so
 * we simply scan for ORT instead of PORT...
 * DCC doesn't have this problem because there's other stuff
 * in the packet before the DCC command.
 *
 * Return 1 if the SLIRPmbuf m is still valid and should be
 * sbappend()ed
 *
 * NOTE: if you return 0 you MUST m_free() the SLIRPmbuf!
 */
int tcp_emu(so, m) struct SLIRPsocket *so;
struct SLIRPmbuf *m;
{
        u_int n1, n2, n3, n4, n5, n6;
        char buff[256];
        u_int32_t laddr;
        u_int lport;
        char *bptr;

        DEBUG_CALL("tcp_emu");
        DEBUG_ARG("so = %lx", (long)so);
        DEBUG_ARG("m = %lx", (long)m);

        switch (so->so_emu) {
                int x, i;

        case EMU_IDENT:
                /*
                 * Identification protocol as per rfc-1413
                 */

                {
                        struct SLIRPsocket *tmpso;
                        struct sockaddr_in addr;
                        socklen_t addrlen = sizeof(struct sockaddr_in);
                        struct sbuf *so_rcv = &so->so_rcv;

                        memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
                        so_rcv->sb_wptr += m->m_len;
                        so_rcv->sb_rptr += m->m_len;
                        m->m_data[m->m_len] = 0; /* NULL terminate */
                        if (strchr(m->m_data, '\r') || strchr(m->m_data, '\n')) {
                                if (sscanf(so_rcv->sb_data, "%d%*[ ,]%d", &n1, &n2) == 2) {
                                        HTONS(n1);
                                        HTONS(n2);
                                        /* n2 is the one on our host */
                                        for (tmpso = tcb.so_next; tmpso != &tcb; tmpso = tmpso->so_next) {
                                                if (tmpso->so_laddr.s_addr == so->so_laddr.s_addr && tmpso->so_lport == n2 &&
                                                    tmpso->so_faddr.s_addr == so->so_faddr.s_addr && tmpso->so_fport == n1) {
                                                        if (getsockname(tmpso->s, (struct sockaddr *)&addr, &addrlen) == 0)
                                                                n2 = ntohs(addr.sin_port);
                                                        break;
                                                }
                                        }
                                }
                                so_rcv->sb_cc = sprintf(so_rcv->sb_data, "%d,%d\r\n", n1, n2);
                                so_rcv->sb_rptr = so_rcv->sb_data;
                                so_rcv->sb_wptr = so_rcv->sb_data + so_rcv->sb_cc;
                        }
                        m_free(m);
                        return 0;
                }

#if 0
		case EMU_RLOGIN:
		       /*
			* Rlogin emulation
			* First we accumulate all the initial option negotiation,
			* then fork_exec() rlogin according to the  options
			*/
		       {
			       int i, i2, n;
			       char *ptr;
			       char args[100];
			       char term[100];
			       struct sbuf *so_snd = &so->so_snd;
			       struct sbuf *so_rcv = &so->so_rcv;

			       /* First check if they have a priveladged port, or too much data has arrived */
			       if (ntohs(so->so_lport) > 1023 || ntohs(so->so_lport) < 512 ||
				   (m->m_len + so_rcv->sb_wptr) > (so_rcv->sb_data + so_rcv->sb_datalen)) {
				       memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
				       so_snd->sb_wptr += 18;
				       so_snd->sb_cc += 18;
				       tcp_sockclosed(sototcpcb(so));
				       m_free(m);
				       return 0;
			       }

			       /* Append the current data */
			       memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
			       so_rcv->sb_wptr += m->m_len;
			       so_rcv->sb_rptr += m->m_len;
			       m_free(m);

			       /*
				* Check if we have all the initial options,
				* and build argument list to rlogin while we're here
				*/
			       n = 0;
			       ptr = so_rcv->sb_data;
			       args[0] = 0;
			       term[0] = 0;
			       while (ptr < so_rcv->sb_wptr) {
				       if (*ptr++ == 0) {
					       n++;
					       if (n == 2) {
						       sprintf(args, "rlogin -l %s %s",
							       ptr, inet_ntoa(so->so_faddr));
					       } else if (n == 3) {
						       i2 = so_rcv->sb_wptr - ptr;
						       for (i = 0; i < i2; i++) {
							       if (ptr[i] == '/') {
								       ptr[i] = 0;
#ifdef HAVE_SETENV
								       sprintf(term, "%s", ptr);
#else
								       sprintf(term, "TERM=%s", ptr);
#endif
								       ptr[i] = '/';
								       break;
							       }
						       }
					       }
				       }
			       }

			       if (n != 4)
				  return 0;

			       /* We have it, set our term variable and fork_exec() */
#ifdef HAVE_SETENV
			       setenv("TERM", term, 1);
#else
			       putenv(term);
#endif
			       fork_exec(so, args, 2);
			       term[0] = 0;
			       so->so_emu = 0;

			       /* And finally, send the client a 0 character */
			       so_snd->sb_wptr[0] = 0;
			       so_snd->sb_wptr++;
			       so_snd->sb_cc++;

			       return 0;
		       }

		case EMU_RSH:
		       /*
			* rsh emulation
			* First we accumulate all the initial option negotiation,
			* then rsh_exec() rsh according to the  options
			*/
		       {
			       int  n;
			       char *ptr;
			       char *user;
			       char *args;
			       struct sbuf *so_snd = &so->so_snd;
			       struct sbuf *so_rcv = &so->so_rcv;

			       /* First check if they have a priveladged port, or too much data has arrived */
			       if (ntohs(so->so_lport) > 1023 || ntohs(so->so_lport) < 512 ||
				   (m->m_len + so_rcv->sb_wptr) > (so_rcv->sb_data + so_rcv->sb_datalen)) {
				       memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
				       so_snd->sb_wptr += 18;
				       so_snd->sb_cc += 18;
				       tcp_sockclosed(sototcpcb(so));
				       m_free(m);
				       return 0;
			       }

			       /* Append the current data */
			       memcpy(so_rcv->sb_wptr, m->m_data, m->m_len);
			       so_rcv->sb_wptr += m->m_len;
			       so_rcv->sb_rptr += m->m_len;
			       m_free(m);

			       /*
				* Check if we have all the initial options,
				* and build argument list to rlogin while we're here
				*/
			       n = 0;
			       ptr = so_rcv->sb_data;
			       user="";
			       args="";
			       if (so->extra==NULL) {
				       struct SLIRPsocket *ns;
				       struct tcpcb* tp;
				       int port=atoi(ptr);
				       if (port <= 0) return 0;
		       if (port > 1023 || port < 512) {
			 memcpy(so_snd->sb_wptr, "Permission denied\n", 18);
			 so_snd->sb_wptr += 18;
			 so_snd->sb_cc += 18;
			 tcp_sockclosed(sototcpcb(so));
			 return 0;
		       }
				       if ((ns=socreate()) == NULL)
			 return 0;
				       if (tcp_attach(ns)<0) {
			 free(ns);
			 return 0;
				       }

				       ns->so_laddr=so->so_laddr;
				       ns->so_lport=htons(port);

				       (void) tcp_mss(sototcpcb(ns), 0);

				       ns->so_faddr=so->so_faddr;
				       ns->so_fport=htons(IPPORT_RESERVED-1); /* Use a fake port. */

				       if (ns->so_faddr.s_addr == 0 ||
					       ns->so_faddr.s_addr == loopback_addr.s_addr)
			 ns->so_faddr = alias_addr;

				       ns->so_iptos = tcp_tos(ns);
				       tp = sototcpcb(ns);

				       tcp_template(tp);

				       /* Compute window scaling to request.  */
				       /*	while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
					*		(TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat)
					*		tp->request_r_scale++;
					*/

		       /*soisfconnecting(ns);*/

				       tcpstat.tcps_connattempt++;

				       tp->t_state = TCPS_SYN_SENT;
				       tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;
				       tp->iss = tcp_iss;
				       tcp_iss += TCP_ISSINCR/2;
				       tcp_sendseqinit(tp);
				       tcp_output(tp);
				       so->extra=ns;
			       }
			       while (ptr < so_rcv->sb_wptr) {
		     if (*ptr++ == 0) {
		       n++;
		       if (n == 2) {
			 user=ptr;
		       } else if (n == 3) {
			 args=ptr;
		       }
		     }
			       }

			       if (n != 4)
		     return 0;

			       rsh_exec(so,so->extra, user, inet_ntoa(so->so_faddr), args);
			       so->so_emu = 0;
			       so->extra=NULL;

			       /* And finally, send the client a 0 character */
			       so_snd->sb_wptr[0] = 0;
			       so_snd->sb_wptr++;
			       so_snd->sb_cc++;

			       return 0;
		       }

		case EMU_CTL:
		       {
			       int num;
			       struct sbuf *so_snd = &so->so_snd;
			       struct sbuf *so_rcv = &so->so_rcv;

			       /*
				* If there is binary data here, we save it in so->so_m
				*/
			       if (!so->so_m) {
				 int rxlen;
				 char *rxdata;
				 rxdata=mtod(m, char *);
				 for (rxlen=m->m_len; rxlen; rxlen--) {
				   if (*rxdata++ & 0x80) {
				     so->so_m = m;
				     return 0;
				   }
				 }
			       } /* if(so->so_m==NULL) */

			       /*
				* Append the line
				*/
			       sbappendsb(so_rcv, m);

			       /* To avoid going over the edge of the buffer, we reset it */
			       if (so_snd->sb_cc == 0)
				  so_snd->sb_wptr = so_snd->sb_rptr = so_snd->sb_data;

			       /*
				* A bit of a hack:
				* If the first packet we get here is 1 byte long, then it
				* was done in telnet character mode, therefore we must echo
				* the characters as they come.  Otherwise, we echo nothing,
				* because in linemode, the line is already echoed
				* XXX two or more control connections won't work
				*/
			       if (do_echo == -1) {
				       if (m->m_len == 1) do_echo = 1;
				       else do_echo = 0;
			       }
			       if (do_echo) {
				 sbappendsb(so_snd, m);
				 m_free(m);
				 tcp_output(sototcpcb(so)); /* XXX */
			       } else
				 m_free(m);

			       num = 0;
			       while (num < so->so_rcv.sb_cc) {
				       if (*(so->so_rcv.sb_rptr + num) == '\n' ||
					   *(so->so_rcv.sb_rptr + num) == '\r') {
					       int n;

					       *(so_rcv->sb_rptr + num) = 0;
					       if (ctl_password && !ctl_password_ok) {
						       /* Need a password */
						       if (sscanf(so_rcv->sb_rptr, "pass %256s", buff) == 1) {
							       if (strcmp(buff, ctl_password) == 0) {
								       ctl_password_ok = 1;
								       n = sprintf(so_snd->sb_wptr,
										   "Password OK.\r\n");
								       goto do_prompt;
							       }
						       }
						       n = sprintf(so_snd->sb_wptr,
						"Error: Password required, log on with \"pass PASSWORD\"\r\n");
						       goto do_prompt;
					       }
					       cfg_quitting = 0;
					       n = do_config(so_rcv->sb_rptr, so, PRN_SPRINTF);
					       if (!cfg_quitting) {
						       /* Register the printed data */
       do_prompt:
						       so_snd->sb_cc += n;
						       so_snd->sb_wptr += n;
						       /* Add prompt */
						       n = sprintf(so_snd->sb_wptr, "Slirp> ");
						       so_snd->sb_cc += n;
						       so_snd->sb_wptr += n;
					       }
					       /* Drop so_rcv data */
					       so_rcv->sb_cc = 0;
					       so_rcv->sb_wptr = so_rcv->sb_rptr = so_rcv->sb_data;
					       tcp_output(sototcpcb(so)); /* Send the reply */
				       }
				       num++;
			       }
			       return 0;
		       }
#endif
        case EMU_FTP:                        /* ftp */
                *(m->m_data + m->m_len) = 0; /* NULL terminate for strstr */
                if ((bptr = (char *)strstr(m->m_data, "ORT")) != NULL) {
                        /*
                         * Need to emulate the PORT command
                         */
                        x = sscanf(bptr, "ORT %d,%d,%d,%d,%d,%d\r\n%256[^\177]", &n1, &n2, &n3, &n4, &n5, &n6, buff);
                        if (x < 6)
                                return 1;

                        laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
                        lport = htons((n5 << 8) | (n6));

                        if ((so = solisten(0, laddr, lport, SS_FACCEPTONCE)) == NULL)
                                return 1;

                        n6 = ntohs(so->so_fport);

                        n5 = (n6 >> 8) & 0xff;
                        n6 &= 0xff;

                        laddr = ntohl(so->so_faddr.s_addr);

                        n1 = ((laddr >> 24) & 0xff);
                        n2 = ((laddr >> 16) & 0xff);
                        n3 = ((laddr >> 8) & 0xff);
                        n4 = (laddr & 0xff);

                        m->m_len = bptr - m->m_data; /* Adjust length */
                        m->m_len += sprintf(bptr, "ORT %d,%d,%d,%d,%d,%d\r\n%s", n1, n2, n3, n4, n5, n6, x == 7 ? buff : "");
                        return 1;
                } else if ((bptr = (char *)strstr(m->m_data, "27 Entering")) != NULL) {
                        /*
                         * Need to emulate the PASV response
                         */
                        x = sscanf(bptr, "27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%256[^\177]", &n1, &n2, &n3, &n4, &n5,
                                   &n6, buff);
                        if (x < 6)
                                return 1;

                        laddr = htonl((n1 << 24) | (n2 << 16) | (n3 << 8) | (n4));
                        lport = htons((n5 << 8) | (n6));

                        if ((so = solisten(0, laddr, lport, SS_FACCEPTONCE)) == NULL)
                                return 1;

                        n6 = ntohs(so->so_fport);

                        n5 = (n6 >> 8) & 0xff;
                        n6 &= 0xff;

                        laddr = ntohl(so->so_faddr.s_addr);

                        n1 = ((laddr >> 24) & 0xff);
                        n2 = ((laddr >> 16) & 0xff);
                        n3 = ((laddr >> 8) & 0xff);
                        n4 = (laddr & 0xff);

                        m->m_len = bptr - m->m_data; /* Adjust length */
                        m->m_len += sprintf(bptr, "27 Entering Passive Mode (%d,%d,%d,%d,%d,%d)\r\n%s", n1, n2, n3, n4, n5, n6,
                                            x == 7 ? buff : "");

                        return 1;
                }

                return 1;

        case EMU_KSH:
                /*
                 * The kshell (Kerberos rsh) and shell services both pass
                 * a local port port number to carry signals to the server
                 * and stderr to the client.  It is passed at the beginning
                 * of the connection as a NUL-terminated decimal ASCII string.
                 */
                so->so_emu = 0;
                for (lport = 0, i = 0; i < m->m_len - 1; ++i) {
                        if (m->m_data[i] < '0' || m->m_data[i] > '9')
                                return 1; /* invalid number */
                        lport *= 10;
                        lport += m->m_data[i] - '0';
                }
                if (m->m_data[m->m_len - 1] == '\0' && lport != 0 &&
                    (so = solisten(0, so->so_laddr.s_addr, htons(lport), SS_FACCEPTONCE)) != NULL)
                        m->m_len = sprintf(m->m_data, "%d", ntohs(so->so_fport)) + 1;
                return 1;

        case EMU_IRC:
                /*
                 * Need to emulate DCC CHAT, DCC SEND and DCC MOVE
                 */
                *(m->m_data + m->m_len) = 0; /* NULL terminate the string for strstr */
                if ((bptr = (char *)strstr(m->m_data, "DCC")) == NULL)
                        return 1;

                /* The %256s is for the broken mIRC */
                if (sscanf(bptr, "DCC CHAT %256s %u %u", buff, &laddr, &lport) == 3) {
                        if ((so = solisten(0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
                                return 1;

                        m->m_len = bptr - m->m_data; /* Adjust length */
                        m->m_len += sprintf(bptr, "DCC CHAT chat %lu %u%c\n", (unsigned long)ntohl(so->so_faddr.s_addr),
                                            ntohs(so->so_fport), 1);
                } else if (sscanf(bptr, "DCC SEND %256s %u %u %u", buff, &laddr, &lport, &n1) == 4) {
                        if ((so = solisten(0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
                                return 1;

                        m->m_len = bptr - m->m_data; /* Adjust length */
                        m->m_len += sprintf(bptr, "DCC SEND %s %lu %u %u%c\n", buff, (unsigned long)ntohl(so->so_faddr.s_addr),
                                            ntohs(so->so_fport), n1, 1);
                } else if (sscanf(bptr, "DCC MOVE %256s %u %u %u", buff, &laddr, &lport, &n1) == 4) {
                        if ((so = solisten(0, htonl(laddr), htons(lport), SS_FACCEPTONCE)) == NULL)
                                return 1;

                        m->m_len = bptr - m->m_data; /* Adjust length */
                        m->m_len += sprintf(bptr, "DCC MOVE %s %lu %u %u%c\n", buff, (unsigned long)ntohl(so->so_faddr.s_addr),
                                            ntohs(so->so_fport), n1, 1);
                }
                return 1;

        case EMU_REALAUDIO:
                /*
                 * RealAudio emulation - JP. We must try to parse the incoming
                 * data and try to find the two characters that contain the
                 * port number. Then we redirect an udp port and replace the
                 * number with the real port we got.
                 *
                 * The 1.0 beta versions of the player are not supported
                 * any more.
                 *
                 * A typical packet for player version 1.0 (release version):
                 *
                 * 0000:50 4E 41 00 05
                 * 0000:00 01 00 02 1B D7 00 00 67 E6 6C DC 63 00 12 50 ..... ..g l c..P
                 * 0010:4E 43 4C 49 45 4E 54 20 31 30 31 20 41 4C 50 48 NCLIENT 101 ALPH
                 * 0020:41 6C 00 00 52 00 17 72 61 66 69 6C 65 73 2F 76 Al..R..rafiles/v
                 * 0030:6F 61 2F 65 6E 67 6C 69 73 68 5F 2E 72 61 79 42 oa/english_.rayB
                 *
                 * Now the port number 0x1BD7 is found at offset 0x04 of the
                 * Now the port number 0x1BD7 is found at offset 0x04 of the
                 * second packet. This time we received five bytes first and
                 * then the rest. You never know how many bytes you get.
                 *
                 * A typical packet for player version 2.0 (beta):
                 *
                 * 0000:50 4E 41 00 06 00 02 00 00 00 01 00 02 1B C1 00 PNA........... .
                 * 0010:00 67 75 78 F5 63 00 0A 57 69 6E 32 2E 30 2E 30 .gux c..Win2.0.0
                 * 0020:2E 35 6C 00 00 52 00 1C 72 61 66 69 6C 65 73 2F .5l..R..rafiles/
                 * 0030:77 65 62 73 69 74 65 2F 32 30 72 65 6C 65 61 73 website/20releas
                 * 0040:65 2E 72 61 79 53 00 00 06 36 42                e.rayS...6B
                 *
                 * Port number 0x1BC1 is found at offset 0x0d.
                 *
                 * This is just a horrible switch statement. Variable ra tells
                 * us where we're going.
                 */

                bptr = m->m_data;
                while (bptr < m->m_data + m->m_len) {
                        u_short p;
                        static int ra = 0;
                        char ra_tbl[4];

                        ra_tbl[0] = 0x50;
                        ra_tbl[1] = 0x4e;
                        ra_tbl[2] = 0x41;
                        ra_tbl[3] = 0;

                        switch (ra) {
                        case 0:
                        case 2:
                        case 3:
                                if (*bptr++ != ra_tbl[ra]) {
                                        ra = 0;
                                        continue;
                                }
                                break;

                        case 1:
                                /*
                                 * We may get 0x50 several times, ignore them
                                 */
                                if (*bptr == 0x50) {
                                        ra = 1;
                                        bptr++;
                                        continue;
                                } else if (*bptr++ != ra_tbl[ra]) {
                                        ra = 0;
                                        continue;
                                }
                                break;

                        case 4:
                                /*
                                 * skip version number
                                 */
                                bptr++;
                                break;

                        case 5:
                                /*
                                 * The difference between versions 1.0 and
                                 * 2.0 is here. For future versions of
                                 * the player this may need to be modified.
                                 */
                                if (*(bptr + 1) == 0x02)
                                        bptr += 8;
                                else
                                        bptr += 4;
                                break;

                        case 6:
                                /* This is the field containing the port
                                 * number that RA-player is listening to.
                                 */
                                lport = (((u_char *)bptr)[0] << 8) + ((u_char *)bptr)[1];
                                if (lport < 6970)
                                        lport += 256; /* don't know why */
                                if (lport < 6970 || lport > 7170)
                                        return 1; /* failed */

                                /* try to get udp port between 6970 - 7170 */
                                for (p = 6970; p < 7071; p++) {
                                        if (udp_listen(htons(p), so->so_laddr.s_addr, htons(lport), SS_FACCEPTONCE)) {
                                                break;
                                        }
                                }
                                if (p == 7071)
                                        p = 0;
                                *(u_char *)bptr++ = (p >> 8) & 0xff;
                                *(u_char *)bptr++ = p & 0xff;
                                ra = 0;
                                return 1; /* port redirected, we're done */
                                break;

                        default:
                                ra = 0;
                        }
                        ra++;
                }
                return 1;

        default:
                /* Ooops, not emulated, won't call tcp_emu again */
                so->so_emu = 0;
                return 1;
        }
}

/*
 * Do misc. config of SLiRP while its running.
 * Return 0 if this connections is to be closed, 1 otherwise,
 * return 2 if this is a command-line connection
 */
int tcp_ctl(so) struct SLIRPsocket *so;
{
        struct sbuf *sb = &so->so_snd;
        int command;
        struct ex_list *ex_ptr;
        int do_pty;
        //	struct SLIRPsocket *tmpso;

        DEBUG_CALL("tcp_ctl");
        DEBUG_ARG("so = %lx", (long)so);

#if 0
	/*
	 * Check if they're authorised
	 */
	if (ctl_addr.s_addr && (ctl_addr.s_addr == -1 || (so->so_laddr.s_addr != ctl_addr.s_addr))) {
		sb->sb_cc = sprintf(sb->sb_wptr,"Error: Permission denied.\r\n");
		sb->sb_wptr += sb->sb_cc;
		return 0;
	}
#endif
        command = (ntohl(so->so_faddr.s_addr) & 0xff);

        switch (command) {
        default: /* Check for exec's */

                /*
                 * Check if it's pty_exec
                 */
                for (ex_ptr = exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next) {
                        if (ex_ptr->ex_fport == so->so_fport && command == ex_ptr->ex_addr) {
                                do_pty = ex_ptr->ex_pty;
                                goto do_exec;
                        }
                }

                /*
                 * Nothing bound..
                 */
                /* tcp_fconnect(so); */

                /* FALLTHROUGH */
        case CTL_ALIAS:
                sb->sb_cc = sprintf(sb->sb_wptr, "Error: No application configured.\r\n");
                sb->sb_wptr += sb->sb_cc;
                return (0);

        do_exec:
                DEBUG_MISC((dfd, " executing %s \n", ex_ptr->ex_exec));
                return (fork_exec(so, ex_ptr->ex_exec, do_pty));

#if 0
		case CTL_CMD:
		   for (tmpso = tcb.so_next; tmpso != &tcb; tmpso = tmpso->so_next) {
		     if (tmpso->so_emu == EMU_CTL &&
			 !(tmpso->so_tcpcb?
			   (tmpso->so_tcpcb->t_state & (TCPS_TIME_WAIT|TCPS_LAST_ACK))
			   :0)) {
		       /* Ooops, control connection already active */
		       sb->sb_cc = sprintf(sb->sb_wptr,"Sorry, already connected.\r\n");
		       sb->sb_wptr += sb->sb_cc;
		       return 0;
		     }
		   }
		   so->so_emu = EMU_CTL;
		   ctl_password_ok = 0;
		   sb->sb_cc = sprintf(sb->sb_wptr, "Slirp command-line ready (type \"help\" for help).\r\nSlirp> ");
		   sb->sb_wptr += sb->sb_cc;
		   do_echo=-1;
		   return(2);
#endif
        }
}
